Tube reactors



Nov. 15, 1966 0E ER ET AL TUBE REAGTORS Filed Dec. 15, 1963 INVENTORS: GUENTER POEHLER ANTON WEGERICH OTTO GOEHRE HELLMUT GIEHNE United States Patent O 3,285,713 TUBE REACTORS Guenter Poehler, Ludwigshafen (Rhine), Anton Wegerich, Limburgerhof, Pfalz, Otto Goehre, Heidelberg, and Hellmut Giehne, Limburgerhof, 1fa1z, Germany, assignors t Badische Ani1in- & Soda-Fabrik Aktiengesellschaft, Ludwigshafen (Rhine), Germany Fi1ed Dec. 13, 1963, Sex. N0. 330,366 Claims priority, applicati;max Germany, Dec. 18, 1962,

019 8 Claims. (C1. 23-288) This invention relates to a tube reactor for carrying out endothermic cataflytic reactions. The -reactor is suitab1e fo-r example for the dehydrogenation of :paraflinic and naphthenic hydroca1bons and their derivatives, particu- 1arly for the dehydrogenat-ion -of a1cohols.

Long kilns having built-in heating ooils have hitherto been used for endothermic catalyti-c reactions. It has been very difiioult t-o introduce -into the furna-ce the heat required fo1' the reaction. Very lange Ffurnaces have therefore been neoessary, and these contained considerable amonmts of catalyst in relation to the initial materials intr-oduced. A change-over to tobe reactors then took place in which 1ess catalyst is required and considerab-ly better space-time yie-1ds are a-chieved. In orde-r that the heat supplied may mach into the interior of. the catalyst tubes, tubes having sma'11 internal widths dior eX-arnple of 20 t-o 60 mm. have been chosen. Uniform distribution of temperature is obtaintable in these tubes. To achieve good utilization of space in the reactors, a very lange number of tubes, Ion eXam=ple 4000 to 6,000, is anranged in the reactor. Cha.rging these tubes with pieces of catalyst is very difficult and takes a long time, particulanly as each tube should contain the same amount of oatalyst and offer temperafur is o=btainable in these tubes. 'To achieve ui1ifomn distribution 0f heat in the tobe reactors it is necessary to use a1iquid, for example a hi-gh boiling point 0i1, dipheny1 or the like. Owing -to the wei-ght of these changes, a particulariy expansive oonstr=uction of the l-ower tobe header is necessary.

We have now found that -the said disadvantages in a tube react-or are obviated When the tubes have a diameter heating medium which is passed through the reactor in ooourrrent with the substances 10 be treated.

' The :cylindrical space Which is 1efit free of tubes in the center of The meactor may have a cross-section amounti1ig to about 7 10 25%, -advantageously about 9 to 20%, of the total cross-section ofihe -reactor.

;It is advantaeous 1 0 provide at one end of the reactor a'n annular duct which commun-icates with the interior ofthe reactor by openings for the supply of a heating g'as, and to provide a similar duct at the other end for the withdrawai o-f the heating gas. The point of entry of the heating ggas is advantageous ly construoted so that the current of gas is divided into two portions Whioh pass thmough the annular duct in different directions. This may be achieved f-or exaxrn-ple by -the provision of distributing means in =the shape of the bow of a ship. The openings for the assage of the gas into the interior of the react-or are advantageously formed -as s1ots which gradua=1ly increase in size in the direction of flow. The crosssection of the annular duct should be about to 20%, parti-oula r1y 7 to 16%, of the cross-section of the reactor. The heating gas -is introduced at the end of the reactor a1; which the substances to be treated are introduced into ICC the tubes filled with catalyst, so 1:hat the two pass coourrently through the reaotor. Baflie plates are arran:ged in the eentra1 :part and along the wa'1l of the reaccor so that the main flow of the heating gas is deflected a1ternate1y toward the midd1e and toward the W2l11 of the reactor. These baffle p1ates in the central portion of the reaoto-r should be lamge enough to oocupy a: least 90% of the cantra1 portion of the reactor which is -free of tubes, and preierably lange enough to project into the wart of the reactor provided with tubes. These baffle plates which are arranged substantiaily pempendicular to the tubes have the form of coherent or perforated discs. It is advantageous for uhe portion of these baflies which is in the ortion of the react-or free from 1aubes 10 oe substantiaily closed,

whereas any pontion of the baffles which projects into area occupied by the tu-bes -is advantageously perforated. The discs a-dvantageusly have a size Which is about 25 to 60% of the cross-sectional area of 1he creactor. Further bafiie pla-tes am pnovided along the wall of the reactor, these baflies having the shape of rings in -contact With the wa1l. Their cross-sectional area may be about 50 10 75% of the cross-seotional area of the meactor. Baffle plates are preferred which have as many perforations as possi-ble, the diameter of the perforations being 3 t0 10 mm. depending 011 the size of the reaotor. In this way it is not the wh ole of the stream of gas which is deflected, but some of it passes through the baflie p1ates. Dead corners aae =chus av-oided. The two Iypes of baffle plates are arranged alternately at diiferent heights. It is advantageous t-o arrange the baflie plates so that the heating ggas st-ream first meets a bafl1e p1ate mounted 0n the 1'6- actor wall. The number of bafl1e plates to be installed' in the reactor depends particularly on the 1ength of the.

reaotor. In conventiona-l industrial reaotors, which have a 1ength of a bout 6 to 20 m. the =bafiies are spaced apart by abon1t 50 cm. t0 2 In. Another annuiar duct is provided at the other end o-f the reactor 1;hrough which the heating gas .leaves the reactor. The exhaust gas is heated up and for the most part returned I0 the reactor by means of a b1ower. The heat of the heating mediuan is uniformly distributed over the whole or-oss-section of the individual tubes by the .oons-trmtion of tube reacto-r according to this invention so th-at an equa1 conversi0n is achieved in each tobe. In this way it is possible, in com-' parison With prior art tube reaotors, to choose Lobes having a Iarge diameter and to use a gas instead of a liquid as heating medium. The time required for replacing catalysts may Ihen be shortened considerably. Furthermore the number 013 tu-bes for a given reaction space may be lessened c-onsiderably and the amoun1: of cata1yst in creased. Depending on the le-ngth of the reactor and its diameter which is usual1y about 1 to 5 an., about to 250 tubes are required. The ratio of tube diameter to tube length should be between about 12:1000 and 1721000, and the diameter of the oubes advanta-geously varies between 7 and 12 cm., partiou-lavly 8 10 12 cm. The 1ength of the tubes, with the above-mentioned dimensi-ons of the reactor, may vary between 5 and 12 m. The individual t-ubes are spaced apart from eaoh othor by 15 to 60 mm., particular.ly 20 t-o 50 mm.

A tube reactor constructed in accordance with this in-.

Patented Nov. 15, 1966 lysts having dehydrogenating 01' cracking action, in the forrn f pieces, for example balls, cylinders, pellets and cones. They may consist of metals of groups IB t0 VIII-B of the Periodic Chart (Handbook of Chemistry and Physics, Chernical Rubber Publishing Co. 43rd edition, pp. 448-449), for example copper, zinc, molybdenurn, tungsten, manganese, iron, nickel or cobalt, particularly in the forrn of their compounds, for exarnple oxides, phosphates or halides. The said catalysts n1ay be supported on conventional carrier materials, such as pumice, silicic acid, titanium oxide, alurninas and the like, or carriers having good therrnal conductivity, such as materials COHtaining iron Oxide, for exarnple a substance obtained in the production of aluminurn and containing 50% Fe O 24% A1 O 3% SiO 8% TiO 3% CaO and 4% Nz0.

The invention Will now be described with reference to the accornpanying drawings in which a tube reactor is shown diagrarnrnatically by way of exarnple, FIGURE 1 being a sectional elevation and FIGURE 2 a section on the line A-B of FIGURE 1. FIG. 3 is an end elevation of a fragment of a perforated, peripheral baffle plate and the tubes extending therethrough, and FIG. 4 is an end elevation of a perforated, central baflle plate and the tubes extending therethrough.

Heating gas is introduced through line 1, is divided into two partial strearns by a distributor 9 shaped like a ships bow and then passes into annular duct 2 and through openings 3 into the interior of the reactor. The heating gas is deflected several times in direction during its passage through the reactor by bafile plates 4. The gas then collects at the opposite end of the reactor in an annular duct 5 and is withdrawn through line 6. The substances to be dehydrogenated are introduced into the reactor through inlet 7 and the reaction product leaves the reaotor through pipe 8.

Accordingly, the tube reactor comprises a hollow shell 13 defining the tubular reactor. The hollow shell 13 has a header member or plate 12 extending transversely across the shell near each end thereof. A plurality of tubes 10 extend longitudinally in the shell between the header members 0r plates 12. The tubes are arranged in spaced relationship to each other With the axial center portion 14 of the shell 13 free of said tubes. The transverse crosssection area of the axial center portion 14 is 7-25% of the transverse cross-section cf the shell.

The baffle plates 4 comprise a plurality 0f peripheral baffle plates 4b with center openings and central baffle plates 4a disposed in the shell in alternating, axially spaced relationship, said baflle plates being substantially perpendicular to the longitudinal axis of the shell 13. The peripheral baffle plates 4b have a plurality of small perforations 11b for passage therethrough of a part of the hot gas stream flowing through the shell over the tubes 10. The central baffle plates 4a have, in the peripheral areas extending beyond the axial center portion 14, a plurality of small perforations 11a for sirnilar passage of a part of the hot gas stream. As aforesaid, the perforations eliminate dead spaces in the portions of the shell 13 external of the tubes 10. The central baffles 4a a1e positioned in the axial central portion of the -shell 13 and the peripheral baffles extend inwardly frorn the wall of the shell 13 with the openings thereof in the axial center portion 14 of the shell.

The following examples will further illustrate this invention.

EXAMPLE 1 4,000 kg. per hour of pure cyclohexanol is heated up to about 180 C. in a heat exchanger by means of hot vapors and gases leaving a tube reactor, and is then supplied to a colurnn packed With Raschig rings which is cennected t0 a circulating evaporator. The level of liquid at the bottorn of the column is kept constant. 10 kg. of component s o f high boiling point is withdrawn per hour at the bottorn. The vapors leaving the column are then passed into a second heat exchanger which is heated With reaction product coming direct from the tube reactor and then passed at a temperature of 260 C. into the tube reactor. The reactor contains 117 tubes each having an internal diameter of mm. The diameter of the tube reactor is 1.80 m. and its height is 9 m. Bach of the tubes is 6 m. in length and fi1led With 5 m. of a catalyst consisting of purnice to which 10% by weight of metallic copper has been applied. The tubes are spaced apart from each other by 30 mm., and are parallel to the Wall of the reactor. The space left free in the middle has a crosssection which is about 13% of the cross-section of the reactor. The upper end of the reactor is provided with an annular duct about 1 m. in height whose cross-section is about 10% of the cross-section of the furnace. 35,000

m. (S.T.P.) of heating gas at a temperature of 390 C.

is introduced hourly into this duct. Spaced apart 'by distances of 1.5 rn., bafile plates are arranged alternately on the Wall of the reactor and in the central space of the reactor. The cross-section of the baflle plates provided on the Wall is about 60% of the cross-section of the reactor. The bafile plates in the middle of the reactor crosssection, which is free of tubes, are closed, whereas the part of the baflle plates which projects between the tubes has holes which are 5 mm. in diarneter. The total size of the baflle plates is 45% of the reactor cross-section. The speed of the heating gas, whose flow is deflected several times by the baflle plates within the reactor, is 6.5 m./sec. 3,842 kg. per hour 0f a liquid reaction product is obtained from which by distillation 2,998 kg. of cyclohexanone and 734 kg. of cyclohexanol are obtained.

EXAMPLE 2 By leading 3,000 kg. per hour of secondary butanol through the reactor described in Example 1 under otherwise the same conditions, 2,600 kg. of methyl ethyl ketone is obtained.

We clairn:

1. A tube reactor useful for the catalytic dehydrogenation of alcohols comprising a plurality of tubes in which the ratio of tube diameter to tube length is frorn 12: 1000 to 17: 1000 and the tube diameter is from 70 to 120 mm., said tubes being distributed over the cross-section of the reactor so that a central space is left free from tubes, the cross-sectional area of said central space being from 7 to 25% of the total cross-sectional area of the reactor, a plurality of baflle plates substantially perpendicular to said tubes and located alternately against the reactor Wall and in the center of the cross-section of the reactor to deflect a gaseous heating medium, said central bafile plates having a surface area of 25 to 60% of the total cross-sectional area of said reactor and said baffle plates along the Wall having a surface area of 50 to 75% of the total crosssectional area of said reactor, and annular ducts arranged one at each end of said reactor and having openings communicating With the interior of said reactor for the supply and withdrawal of said gaseous heating medium.

2. A tube reactor useful for catalytic reactions comprising a hollow shell defining a tubular reactor, a header member extending transversely across said shel1 near each end thereof, a plurality of tubes extending longitudinally in said shell between said shell between said header members, said tubes being arranged in spaced relationship to each other With the axial center portion of said shell free of said tubes, the transverse cross section area of said axial center portion being 725% 0f the transverse cross section of said she1l, a plurality of peripheral bafile plates and central baflle plates disposed in said shell between said header plates in axially spaced, alternating relationship, said baflle plates being substantially perpendicular to the longitudinal axis of said shell, said central baffle plates being in the axial central portion of said shell and said peripheral baffies extending inwardly from the Wall cf said shell with an opening therein in said axial center portion of said shell, said peripheral baffle p1ates having sma1l perforations for passage therethrough of a part of a hot gas stream flowing through said shell across said tubes, said central bafl1e plates each having surface area of 25- 60% of the transverse cross section area of said shel1, and said peripheral baffle plates each having a surface area of 50-75 of the transverse cross section area cf said shell.

3. A tube reactor as claimed in c1aim 2, wherein said perforations have a diameter in the range of 3-10 mm.

4. A tube reactor useful for cata1ytic reactions comprising a hollow shell defining a tubular reactor, a header memb'er extending transversely across said shell near each end thereof, a plurality of tubes extending longitudinally in said shell between said header members, said tubes being arranged in spaced relationship to each other with the axial center portion of said shell free of said tubes, the transverse cross section area of said axial center portion being 7-25 of the transverse cross section of said shell, a plurality of peripheral baflie plates and central baffle plates disposed in said shell between said header plates in axially spaced, alternating relationship, said bafl*le plates being substantially perpendicular to the longitudinal axis of said shell, said central bafl1e plates being in the axial central portion of said shell and said peripheral bafl1es extending inwardly from the wa1l of said shell with an opening therein in said axial unter portion of said she1l, said centra1 bafl1e plates having peripheral areas ex tending beyond said axial ccnter portion into a part of the area occupied by said tubes, said peripheral areas having small perforations for passage therethrough of a part of a hot gas stream flowing through said shell across said tubes, said. central baflie plates each having surface area of 2560% of the transverse cross section area of said shell, and said peripheral baffle plates each having a surface area of -75% of the transverse cross section area of said shell.

5. A tube reactor as clairned in claim 4, wherein said shell has an annular, hot gas feed duct thereabout, and said she1l has a plurality of openings distributed about its circumference and communicating said duct With the tubecontaining portion of said shell near one of said header members.

6. A tube reactor as claimed in claim 4, wherein said perforations have a diameter in the range of 3-10 mm.

7. A tube reactor as claimed in claim 4, wherein the ratio of tube diameter to tube length is from 12:1000 to 17: 1000 with a diameter 0f the tubes 01: from to S. A tube reactor as claimed in claim 4, wherein said cross-sectional area of said axial center portion is about 9 to 20% of the transverse cross-sectional area of said shell.

References Cited by the Examiner UNITED STATES PATENTS 1,900857 3/1935 Berry et a1. 23288 2,411,097 11/1946 Kopp.

FOREIGN PATENTS 438,177 3/1912 France.

MORRIS O. WOLK, Primary Examiner.

JAMES H. TAYMAN, JR., Examz'ner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent N0. 3285713 November 15, 1966 Guenter Poehler et a1.

It is hereby certified that error appears in the above numbered patent requiring correction and that ehe seid Letters Patent should read as corrected below.

Column l, lines 35 and 36, strike out "and offer temperature is obtainable in these tubes." and insert instead and offer the same resistance to the passage of vapors. line 55, for "advantaeous" read advantageous column 2, line 46, -for "large" read larger column 4, line 63 strike out "said shell between", second occurrence.

Signed and sealed this 7th day of November 1967.

(SEAL) Attest:

Edward M. Fletcher, J r. EDWARD J. BRENNER Attesting Officer Commissioner of Patents 

1. A TUBE REACTOR USEFUL FOR THE CATALYTIC DEHYDROGENATION OF ALCOHOLS COMPRISING A PLURALITY OF TUBES IN WHICH THE RATIO OF TUBE DIAMETER OF TUBE LENGTH IA DEOM 12:1000 TO 17:1000 AND THE TUBE DIAMETER IS FROM 70 TO 120 MM., SAID TUBES BEING DISTRIBUTED OVER THE CROSS-SECTION OF THE REACTOR SO THAT A CENTRAL SPACE IS LEFT FREE FROM TUBES, THE CROSS-SECTIONAL AREA OF SAID CENTRAL SPACE BEING FROM 7 TO 25%% OF THE TOTAL CROSS-SECTIONAL AREA OF THE REACTOR, A PLURALITY OF BAFFLE PLATES SUBSTANTIALLY PERPENDICULAR TO SAID TUBES AND LOCATED ALTERNATELY AGAINST THE RECTOR WALL AND IN THE CENTER OF THE CROSS-SECTION OF THE REACTOR TO DEFLECT A GASEOUS HEATING MEDIUM, SAID CENTRAL BAFFLE PLATES HAVING A SURFACE AREA OF 25 TO 60% OF THE TOTAL CROSS-SECTIONAL AREA OF SAID REACTOR AND SAID BAFFLE PLATES ALONG THE WALL HAVING A SURFACE AREA OF 50 TO 75% OF THE TOTAL CROSSSECTIONAL AREA OF SAID REACTOR, AND ANNULAR DUCTS ARRANGED ONE AT EACH END OF SAID REACTOR AND HAVING OPENINGS COM MUNCATING WITH THE INTERIOR OF SAID REACTOR FOR THE SUPPLY AND WITHDRAWAL OF SAID GASEOUS HEATING MEDIUM. 